Depends on the strength of the medicine, number of doses, time between doses.Don`t know why you would take 9 in one night, plus another medication, but a Dr is just a phone call away……(or the ER, whichever you can do first…)

Determining how long muscle relaxers stay in your system really all depends on a persons body weight. Most muscle relaxers can stay in your system for 36 hours to even a few days. Drinking plenty of water after taking them helps to flush it

Muscle relaxants are in the toolbox of ways to treat chronic by the drug. Under the supervision of your doctor, you can stay on tizanidine indefinitely, because it is not habit-forming. Chronic headaches can be debilitating to long- term sufferers. Stress has negative side effects on nearly every part of the body. Detail:http://www.ehow.com/how_2163692_use-muscle-relaxants-treat-chronic.html